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Commit cc3d967f authored by Ladi Prosek's avatar Ladi Prosek Committed by Radim Krčmář
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KVM: SVM: detect opening of SMI window using STGI intercept 



Commit 05cade71 ("KVM: nSVM: fix SMI injection in guest mode") made
KVM mask SMI if GIF=0 but it didn't do anything to unmask it when GIF is
enabled.

The issue manifests for me as a significantly longer boot time of Windows
guests when running with SMM-enabled OVMF.

This commit fixes it by intercepting STGI instead of requesting immediate
exit if the reason why SMM was masked is GIF.

Fixes: 05cade71 ("KVM: nSVM: fix SMI injection in guest mode")
Signed-off-by: default avatarLadi Prosek <lprosek@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 9b8ebbdb

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1065,6 +1065,7 @@ struct kvm_x86_ops { 
	int (*smi_allowed)(struct kvm_vcpu *vcpu);

	int (*smi_allowed)(struct kvm_vcpu *vcpu);

	int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);

	int (*pre_enter_smm)(struct kvm_vcpu *vcpu, char *smstate);

	int (*pre_leave_smm)(struct kvm_vcpu *vcpu, u64 smbase);

	int (*pre_leave_smm)(struct kvm_vcpu *vcpu, u64 smbase);

	int (*enable_smi_window)(struct kvm_vcpu *vcpu);

};

};





struct kvm_arch_async_pf {

struct kvm_arch_async_pf {

arch/x86/kvm/svm.c

+15 −1
Original line number Original line Diff line number Diff line
@@ -3187,7 +3187,7 @@ static int stgi_interception(struct vcpu_svm *svm) 




	/*

	/*

	 * If VGIF is enabled, the STGI intercept is only added to

	 * If VGIF is enabled, the STGI intercept is only added to

	 * detect the opening of the NMI window; remove it now.

	 * detect the opening of the SMI/NMI window; remove it now.

	 */

	 */

	if (vgif_enabled(svm))

	if (vgif_enabled(svm))

		clr_intercept(svm, INTERCEPT_STGI);

		clr_intercept(svm, INTERCEPT_STGI);
@@ -5476,6 +5476,19 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase) 
	return ret;

	return ret;

}

}





static int enable_smi_window(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);



	if (!gif_set(svm)) {

		if (vgif_enabled(svm))

			set_intercept(svm, INTERCEPT_STGI);

		/* STGI will cause a vm exit */

		return 1;

	}

	return 0;

}



static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

	.cpu_has_kvm_support = has_svm,

	.cpu_has_kvm_support = has_svm,

	.disabled_by_bios = is_disabled,

	.disabled_by_bios = is_disabled,
@@ -5590,6 +5603,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { 
	.smi_allowed = svm_smi_allowed,

	.smi_allowed = svm_smi_allowed,

	.pre_enter_smm = svm_pre_enter_smm,

	.pre_enter_smm = svm_pre_enter_smm,

	.pre_leave_smm = svm_pre_leave_smm,

	.pre_leave_smm = svm_pre_leave_smm,

	.enable_smi_window = enable_smi_window,

};

};





static int __init svm_init(void)

static int __init svm_init(void)

arch/x86/kvm/vmx.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -11973,6 +11973,11 @@ static int vmx_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase) 
	return 0;

	return 0;

}

}





static int enable_smi_window(struct kvm_vcpu *vcpu)

{

	return 0;

}



static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {

static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {

	.cpu_has_kvm_support = cpu_has_kvm_support,

	.cpu_has_kvm_support = cpu_has_kvm_support,

	.disabled_by_bios = vmx_disabled_by_bios,

	.disabled_by_bios = vmx_disabled_by_bios,
@@ -12102,6 +12107,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { 
	.smi_allowed = vmx_smi_allowed,

	.smi_allowed = vmx_smi_allowed,

	.pre_enter_smm = vmx_pre_enter_smm,

	.pre_enter_smm = vmx_pre_enter_smm,

	.pre_leave_smm = vmx_pre_leave_smm,

	.pre_leave_smm = vmx_pre_leave_smm,

	.enable_smi_window = enable_smi_window,

};

};





static int __init vmx_init(void)

static int __init vmx_init(void)

arch/x86/kvm/x86.c

+14 −8
Original line number Original line Diff line number Diff line
@@ -6892,16 +6892,22 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
		if (inject_pending_event(vcpu, req_int_win) != 0)

		if (inject_pending_event(vcpu, req_int_win) != 0)

			req_immediate_exit = true;

			req_immediate_exit = true;

		else {

		else {

			/* Enable NMI/IRQ window open exits if needed.

			/* Enable SMI/NMI/IRQ window open exits if needed.

			 *

			 *

			 * SMIs have two cases: 1) they can be nested, and

			 * SMIs have three cases:

			 * then there is nothing to do here because RSM will

			 * 1) They can be nested, and then there is nothing to

			 * cause a vmexit anyway; 2) or the SMI can be pending

			 *    do here because RSM will cause a vmexit anyway.

			 * because inject_pending_event has completed the

			 * 2) There is an ISA-specific reason why SMI cannot be

			 * injection of an IRQ or NMI from the previous vmexit,

			 *    injected, and the moment when this changes can be

			 * and then we request an immediate exit to inject the SMI.

			 *    intercepted.

			 * 3) Or the SMI can be pending because

			 *    inject_pending_event has completed the injection

			 *    of an IRQ or NMI from the previous vmexit, and

			 *    then we request an immediate exit to inject the

			 *    SMI.

			 */

			 */

			if (vcpu->arch.smi_pending && !is_smm(vcpu))

			if (vcpu->arch.smi_pending && !is_smm(vcpu))

				if (!kvm_x86_ops->enable_smi_window(vcpu))

					req_immediate_exit = true;

					req_immediate_exit = true;

			if (vcpu->arch.nmi_pending)

			if (vcpu->arch.nmi_pending)

				kvm_x86_ops->enable_nmi_window(vcpu);

				kvm_x86_ops->enable_nmi_window(vcpu);